Method and system for removing contaminants from soil

Abstract

A method and system for removing contaminants from contaminated soil at a site utilizes particle size segregation and particle density segregation to yield a plurality of fractions, whereby each of the fractions are tested and identified for the presence of unacceptable levels of contaminants, and the soil fractions from the contaminated soil at the site corresponding to the identified contaminated fractions are collected for subsequent disposal or treatment, while the remaining untainted soil fractions are homogenized and returned to the site.

1. A method for removing contaminants from contaminated soil at a site, comprising the steps of:
 soil diagnostic testing including the steps of:
 extracting a representative sample of the contaminated soil from the site; 
 segregating the sample into a plurality of size fractions according to particle size without any testing for contaminants being made; 
 segregating each of the size fractions into a plurality of density fractions according to particle density prior to testing for contaminants; 
 testing the plurality of density fractions to identify those containing the presence of unaccepteble levels of contaminants representing at least a portion of the total contaminant amount of the sample; and 
 
 field system design and implementation based upon said soil diagnostic testing including the steps of:
 extracting the contaminated soil from the site; 
 
 isolating soil fractions from the contaminated soil at the site corresponding to the identified contaminated density fractions from the sample;
 processing the isolated soil fractions to remove the contaminants therefrom; 
 treating the processed soil fractions from the site corresponding to the identified contaminated fractions with at least one stabilization reagent capable of inhibiting the solubility of metal contaminants from the processed soil; and 
 returning the treated soil fractions to the site. 
 
 
   
   
     2. The method of  claim 1  further including the step of reconstituting soil fractions deemed to contain acceptable levels of contamination to the site. 
   
   
     3. The method of  claim 1 , further including the step of treating the soil fractions containing the unacceptable levels of contaminants to remove the contaminants therefrom. 
   
   
     4. The method of  claim 3 , further including the step of restoring the treated soil fractions back to the site. 
   
   
     5. The method of  claim 1 , wherein the total contaminant amount includes particulate and leachable contaminants. 
   
   
     6. The method of  claim 1 , wherein the particle size segregation step comprises utilizing dry separation, and implementing a wet wash to separate the coarser fraction from the finer fraction. 
   
   
     7. The method of  claim 1 , wherein the particle size segregation step comprises utilizing a wet separation process. 
   
   
     8. The method of  claim 1 , wherein the density segregation step comprises utilizing a gravity separation process. 
   
   
     9. The method of  claim 1 , further including the step of removing ferromagnetic material from the soil fractions. 
   
   
     10. The method of  claim 1 , further comprising treating the soil fractions from the site corresponding to the identified contaminated fractions with at least one microbial agent. 
   
   
     11. The method of  claim 1 , wherein the density segregation step comprises elutriating the particle size fractions. 
   
   
     12. The method of  claim 1  wherein the density segregation step comprises jigging the particle size fractions. 
   
   
     13. The method of  claim 1 , further including the step of removing vegetation from the soil fractions. 
   
   
     14. The method  claim 1 , further including the step of treating the soil fractions from the site corresponding to the identified contaminated fractions with at least one oxidizing agent. 
   
   
     15. The method  claim 1  further comprising treating the soil fractions form the site corresponding to the identified fractions with at least one reducing agent. 
   
   
     16. The method of  claim 1 , wherein the density segregation step comprises generating a first density fraction having a specific density corresponding to vegetative matter, a second fraction having a specific density corresponding to metal and a third density fraction having a specific density intermediate of the vegetative matter and metal. 
   
   
     17. The method of  claim 16 , wherein the specific density of the first density fraction is in the range of from about 0.8 to 1.2. 
   
   
     18. The method of  claim 16 , wherein the specific density of the second density fraction is at least 8. 
   
   
     19. The method of  claim 16 , wherein The specific density of the third density fraction is in the range of from about 2.5 to 3.5. 
   
   
     20. The method of  claim 1 , wherein the stabilization reagent is capable of stabilizing the metal contaminants by chemically bonding them into a mineral form or other low solubility phases o complexes that are stable over a long period of time. 
   
   
     21. The method of  claim 1 , wherein the stabilization reagent is selected from the group consisting of mineral apatites, flocculants, pre-mixed flocculants and mixtures thereof. 
   
   
     22. The method of  claim 21 , wherein the stabilization reagent is apatite II. 
   
   
     23. A method for removing contaminants from contaminated soil at a site, comprising the steps of:
 soil diagnostic testing including the steps of:
 extracting a representative sample of the contaminated soil from the site; 
 segregating the sample into a plurality of size fractions according to particle size without any testing for contaminants being made; 
 segregating each of the size fractions into a plurality of density fractions according to particle density into a first density fraction having a specific density corresponding to vegetative matter, a second fraction having a specific density corresponding to metal, and a third density fraction having specific density intermediate of the vegetative matter and metal, prior to testing for contaminants; 
 testing the plurality of density fractions to identify those containing the presence of unacceptable levels of contaminants representing at least a portion of the total contaminant amount of the sample; and 
 
 field system design and implementation based upon said soil diagnostic testing including the steps of:
 extracting the contaminated soil from the site; 
 isolating soil fractions from the contaminated soil at the site corresponding to the identified contaminated density fractions from the sample; 
 processing the isolated soil fractions to remove the contaminants therefrom; and 
 returning the processed soil fractions to the site. 
 
 
   
   
     24. The method of  claim 23 , further including the step of treating the processed soil fractions from the site corresponding to the identified contaminated fractions with at least one stabilization reagent capable of inhibiting the solubility of metal contaminants from the processed soil. 
   
   
     25. The method of  claim 24 , wherein the stabilization reagent is capable of stabilizing the metal contaminants by chemically bonding them into a mineral form or other low solubility phases or complexes that are stable over a long period of time. 
   
   
     26. The method of  claim 24 , wherein the stabilization reagent is selected from the group consisting of mineral apatites, flocculants, pre-mixed flocculants and mixtures thereof. 
   
   
     27. The method of  claim 26 , wherein the stabilization reagent is apatite II. 
   
   
     28. The method of  claim 23 , wherein the specific density of the first density fraction is in the range of from about 0.8 to 1.2. 
   
   
     29. The method of  claim 23 , wherein the specific density of the second density fraction is at least 8. 
   
   
     30. The method of  claim 23 , wherein the specific density of the third density fraction is in the range of from about 2.5 to 3.5.